Field of the Invention
The present invention relates to an automatic transmission for a vehicle. More particularly, the present invention relates to a planetary gear train of an automatic transmission for a vehicle which is capable of implementing eleven forward speeds using a minimum number of configurations and improving power transfer performance to reduce fuel consumption.
Description of Related Art
Recently, increasing oil prices have placed intense pressure on manufacturers to produce more fuel-efficient vehicles. Particularly in the case of engines, manufacturers have been pursuing efforts to reduce the weight and improve fuel efficiency of vehicles by reducing engine size, etc.
As a result, research into reduction of weight and enhancement of fuel efficiency through down-sizing has been conducted in the case of an engine and research for simultaneously improving fuel efficiency, and operability and competitiveness in fuel efficiency through providing multiple speed stages has been conducted in the case of an automatic transmission.
However, in the automatic transmission, as the transmission speeds or stages increases, the number of internal components increases, and as a result, the automatic transmission may be difficult to mount, the manufacturing cost and weight may be increased, and power transmission efficiency may be deteriorated.
Accordingly, development of a planetary gear train which may bring about maximum efficiency with a small number of components is important in order to increase a fuel efficiency enhancement effect through the multiple speed stages.
In this aspect, in recent years, 8 and 9-speed automated transmissions tend to be implemented and the research and development of a planetary gear train capable of implementing more transmission steps has also been actively conducted.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.